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Carmen Electra's loose locks add another dimension of sex appeal to this blue backless dress, but she doesn't cross the line.

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Thanks to Diane Kruger, we have sassy and trashy! On the left, Kruger is all elegance and style and on the right... not so much. Let's just say a coin slot lands you on the trashy list.

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Kate Hudson knows she's got the goods. Gold is clearly her color; the fit is perfect; and this low-cut strappy back doesn't give too much away.

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Jessica Alba's gown is sporty and sexy, without being too bootylicious.

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OK, folks, here's the rule: plunging backs that reveal (ahem) things on the front fall on the trashy side. So, while Lindsay Lohan's asymmetrical back is a great cut in theory, it is nothing if not trashy.

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O. M. G. Seriously, Juliette Lewis???

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Molly Sims totally rocks this low-back look. The strap detailing, the gathered back and the stylish accessories make this look pop.

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Remember Mischa Barton before her breakdown? She used to have such lovely looks, like this strappy off-center silver gown. How we pine for the fashionable days of yore.

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Normally ruching helps mask bulges. Not so with the backside of Kim Kardashian's dress. Everything seems fine with the racerback until we cast our gaze further south.

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Apparently Donni Rai is some kind of singer. (Who knew?!) But we could not resist including her because this is, quite frankly, the trashiest backside we've seen. And, yes, we are talking about the dress, although the pose certainly isn't helping matters.

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Again, we repeat the rule... if your plunging back reveals something up front, it ain't sassy. Do you hear that, Katie Price?

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Nicole Kidman just goes to show that not all beaded black gowns are completely classy. The actress looks like she was poured into this dress, and while it's clearly stunning, it's making us a little nervous.

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If Members Only designed an open-backed dress, this is what we imagine it would look like. Hardly sexy, this beige ensemble falls flat on Anne Hathaway.

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How we love Bai Ling, for she keeps our fashion faux pas galleries in business. And this backless number is no exception. Perhaps it was meant to be an apron???

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Sienna Miller reminds us it's not how much you wear, but how you wear it. She looks absolutely stunning in this beaded gown.

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When do you think Tara Reid will stop dressing like she's a sorority girl on spring break in Fort Lauderdale? When's she's 30? (Nope, she's past that already.) When she's 40? We can only hope...

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And here she is again, poor thing. We wanted to like this dress. Really, we did. It's interesting and all the ingredients are there, but it just... doesn't... work. Sorry, Tara.

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OK. One more time. Are you listening, Lisa Rinna? If the back reveals something up front, it's trashy.

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Hayden Panettiere's racer back straps keeps things sporty and stylish without going over the edge.

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We never thought we'd say this, but Brooke Hogan's outfit actually doesn't look bad. The orange suits her and the open back doesn't cross the line into trampy town.

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It's a sassy and trashy two-fer, compliments of Eva Longoria! On the left, she is elegance and grace. On the right, well... let's just say a backdoor zipper designed and placed thusly ain't exactly sassy.

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Camila Alves, known for her relationship with Matthew McConaughey, made our list for Sassy or Trashy: Necklines with this exact, same dress. Seriously, is there even a top to this thing? We've spelled out the rule, Miss Alves, and you fall on the trashy side.

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Ali Larter's dress definitely takes the plunge, but without a coin slot or frontal reveal, it works... it's sexy without being trashy.

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Kristen Stewart is young. She gets to make mistakes. We just hope she learns from this one as follows... peach is not her color, vertical stripes don't help, and short sleeves don't belong on backless dresses.

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The racer-back straps and impeccable fit make this low-back look a stunner for Charlize Theron.

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Getty ImagesThe Last House on the Left's Sara Paxton's royal blue outfit with open back is flirty and chic without going overboard.

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It looks like AnnaLynne McCord had a tapestry pull installed on the back of her dress.

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Sigh. No, no, no, Omarosa. While there's nothing wrong with the dress itself, per se, it just isn't working for you. And if it's not working for you, it's working against you.

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We're intrigued by Ashley Olsen's flowing white gown, but we can't help but wish it were her size. It's like she's hiding in it instead of wearing it.

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While we appreciate the asymmetrical back strap, Taraji P. Henson's dress just misses the mark. Maybe it's the hardware on the strap that makes it feel biker-ish... or maybe it's the back tatt.

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Maggie Gyllenhaal has been known to make some odd fashion choices from time to time. (We know, shocking!) But she strikes just the right note with this sleek backless gown.

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Christina Ricci's 70's-esque look with open back and chain belt has an updated, modern feel.

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Not only does it look like someone attached party ribbon to a scarf and called it a dress, but it's barely staying on former Victoria's Secret model Karolina Kurkova.

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Model Amber Valetta strikes just the right look with her low-cut gown.

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The open back and clinging fit make Ciara's gown too bootylicious to end up on the sassy side of things.

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Eh. Unless Kate Bosworth was going for a limp dress effect, we consider this open back dress a fashion fail.